1. Field of the Invention
This invention relates to manufacturing processes for bending metal, and more particularly to a method for bending steel tubing.
2. Description of Related Art
Metal tubing has a variety of uses and a variety of applications. A typical use of metal tubing is as a conduit for transporting fluid. Automobile manufacturers typically incorporate metal tubing in the design of automobiles for the purpose of transporting fluids. An example of the use of metal tubing in a vehicle is a fuel line. In order for a fuel line to be properly routed in a vehicle a number of bends may be necessary.
When metal tubing is being used as a conduit to transport fluid, such as fuel in a fuel line, avoiding restrictions to the flow is necessary to optimize system efficiency. When metal tubing is bent, the outside diameter of the bend radius typically experiences a collapse. The collapse creates a reduction in flow area; flow area is the cross-sectional area perpendicular to the fluid flow field. When flow area is reduced the result is a restriction to fluid flow.
In order to achieve a minimum collapse of the tubing wall as a result of bending, an appropriate bend radius must be selected. For example, a 3/8 inch O.D. steel tubing must have a bend radius of three inches to achieve a minimum collapse of the wall of the tubing whereby the reduction in the flow area is in the range of 11-15%. However, this bend radius may pose problems in the event that the radius is too large to achieve adequate routing. In this particular instance it may be necessary to substitute a connector, such as a "banjo connector," for the bent section of tubing. The disadvantage of using a connector such as a banjo connector is the high cost in comparison to bending the steel tubing. Therefore, there is a need for an improved method of bending tubing where the collapse of the tubing wall is minimized while also substantially reducing the required bend radius to achieve the desired minimum wall collapse.